4 min read · Sky
Astronomers describe where the Sun is with two numbers: how high it is above the horizon, and which compass direction it is in. Once you know those, questions like “which way will my balcony face at 5 PM?” become easy to answer.
Altitude and azimuth
Altitude (or elevation) is the angle of the Sun above the horizon: 0° at sunrise and sunset, 90° directly overhead. Negative values mean the Sun is below the horizon.
Azimuth is the compass direction: 0° is north, 90° east, 180° south, and 270° west. Together, altitude and azimuth pin down exactly where to look.
Solar noon is rarely 12:00
Solar noon is the moment the Sun is highest in the sky for the day. It is almost never exactly 12:00 on the clock, for three reasons. Time zones are wide, so most places are east or west of the zone’s central meridian. Daylight saving time pushes solar noon about an hour later, toward 1 PM. And Earth’s tilted, elliptical orbit shifts solar noon earlier or later by up to about 16 minutes over the year.
The Sun is only overhead in the tropics
The Sun can only be directly overhead between the Tropic of Cancer and the Tropic of Capricorn (about 23.4° north and south of the equator). Everywhere else, at solar noon the Sun is due south if you live in the Northern Hemisphere, or due north in the Southern Hemisphere.
The Sun doesn’t always rise due east
The Sun rises due east and sets due west only around the March and September equinoxes. Around the June solstice it rises north of east and sets north of west, everywhere on Earth. Around the December solstice it rises south of east. The farther you are from the equator, the bigger that swing.
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